Harbin Institute of Technology

Pengcheng Hu

Jiubin Tan

Jiahao Guo

Di Chang

Xu Xing

Jing Li

Xiaofei Diao

Hongxing Yang

The present disclosure relates to a collaborative phase-shift laser ranging device based on differential modulation and demodulation of coarse and precise measuring wavelength and a ranging method thereof. A collaboration terminal is disposed at a target to be measured of a phase-shift laser ranging system, which can improve the intensity of measurement light and then irradiate the same back to a measuring terminal, thereby resolving the problem of low ranging accuracy caused by the attenuation of light intensity during long-distance ranging. The collaboration terminal detects coarseness gauge signals and modulates a laser source by means of differential modulation; the collaboration terminal detects precision gauge signals by means of difference frequency demodulation, and then the intensity of measurement light is improved by mixing and restoring the precision gauge signals and modulating the collaboration-terminal laser source.

Collaborative phase-shift laser ranging device based on differential modulation and demodulation of coarse and precise measuring wavelength and ranging method thereof

Present disclosure relates to a heterodyne grating interferometric method and system for two-degree-of-freedom with high tolerance. The system comprises a separately modulated heterodyne laser (), an optical prism () and a photoelectric detection and signal processing unit (). The separately modulated heterodyne laser () simultaneously outputs two laser beams at different frequencies, which are incident in parallel to a first beamsplitting surface so as to be split, and then a part thereof is incident to a retro-reflector () to produce reference beams (), which are incident to a third beamsplitting surface, and the other part traverses a double-diffraction structure formed by a measured grating () and retro-reflectors () to obtain two measured beams (), which are incident to a second beamsplitting surface and then are divided into two parts. Wherein one part is converged to form a first interference beam (), and the other part is incident to the third beamsplitting surface and is converged with the corresponding reference beams () to form second and third interference beams (). Photoelectric detection and signal processing is performed on the interference signals of the three interference beams (), so as to calculate horizontal and vertical displacement of the grating (). The present measurement method and system improve the angular tolerance of tip and tilt of the optical grating () while increasing the fold factors.

Heterodyne grating interferometric method and system for two-degree-of-freedom with high alignment tolerance

A method for measuring a dip angle of oppositely crossly placed paired quartered ring-quartered circle nested polar plates. An annular coplanar capacitance measuring head of a sensor unit consists of four quarter round metal plates and four quarter circular-ring-shaped metal plates, the eight metal plates are coplanar and concentric with one another, and a quarter round metal plate and a quarter circular-ring-shaped metal plate corresponding to the same sector angle form a capacitor. Two annular coplanar capacitance measuring heads are arranged on two round insulating substrates, the two round insulating substrates are used as two bottom surfaces of a cylindrical container, the cylindrical container is transversely arranged, and an insulating liquid equal to &#xbd; volume of the cylindrical container is injected into the cylindrical container in a sealing manner. Potential leads extract potentials of the sixteen metal plates and are connected to an input end of a capacitance measuring unit, and the capacitance measuring unit is connected to a dip measuring unit. When the cylindrical container tilts, the relative positions of the two annular coplanar capacitance measuring heads and the insulating liquid are changed, and a dip angle value can be calculated by measuring the change of a capacitance value. Also disclosed is a device for measuring a dip angle of oppositely crossly placed paired quartered ring-quartered circle nested polar plates.

Method and device for measuring dip angle of oppositely crossly placed paired quartered ring-quartered circle nested polar plates

A high speed high resolution heterodyne interferometric method and system are provided. The invention uses two spatially separated beams with slightly different frequencies and has two measurement signals with opposite Doppler shift. The switching circuit selects one of the two measurement signals for displacement measurement according to the direction and speed of the target movement. In this invention, the measurement is insensitive to the thermal variation; the periodic nonlinearity is essentially eliminated by using two spatially separated beams; the measurable target speed of the interferometer is no longer limited by the beat frequency of the laser source.

Growing community of inventors

Heilongjiang, China

Pengcheng Hu